The Photo-Acoustic Research Laboratory (PAR) directed by Professor Cetin Cetinkaya has been conducting analytical, computational and experimental studies in the areas of laser-based particle removal and non-contact nano-adhesion measurements since 1999. There is an immense need in various industries for dry removal of micro/nano-particles (especially in 100-nm range) from blank and patterned substrates. PAR Lab has developed a novel dry cleaning method to remove micron and submicron particles. The approach, based on laser-induced plasma shockwaves, is a non-contact method and the removal efficiency is an order of magnitude higher than the traditional laser cleaning methods. Recent experiments have proved that a latex particle with a diameter of 60 nm and larger particles can be removed from silicon surfaces without damage. The dry laser cleaning method is being used to remove micron and submicron particles from varying substrates as well as from micro-holes and semiconductor trenches. The research in this area at the PAR Laboratory has been supported by Intel Corp., International SEMATECH and Praxair/Electronics.

Modeling of the Chemical-Mechanical Polishing Process

Professor Ahmadi and his group have developed mechanical wear models for the chemical-mechanical polishing process. The work shows the importance of abrasive particles and wafer surface hardness, and the double layer forces on the removal rate. Their analysis includes the influence of abrasive particle adhesion to the surface of the wafer and the variation of surface hardness due to the presence of slurry. In addition Professor Ahmadi and his students are studying the effect of abrasive particle shapes, slurry pH, and colloidal forces on the removal rate.

Professor R. Shankar Subramanian is working on interfacial phenomena and their influence on transport problems. Current areas of research include chemical-mechanical polishing, drop motion on a solid surface, and gas bubble dissolution. In collaboration with his graduate student Vikram Pratap, Professor Subramanian is studying the motion of a liquid drop on a solid surface because of the action of a temperature gradient. Such motion can be important in applications such as the removal of debris in ink jet printing, and in moving drops from one place to another in microfluidic devices. He is also investigating the role of colloidal particles adsorbed at the surface of a bubble or drop in arresting dissolution.

Correlation Between Pad Structures and CMP Performance

Working with a team of scientists at Mipox including Toshihiro Kobayashi and Jun Watanabe, CAMP Professor Yuzhuo Li, CMP facility manager Craig Burkhard, graduate student Krishnayya Cheemalapati , and postdoctoral associate Changxue Wang have been studying the effectiveness of a new pad. Unlike conventional porous pads, the new pad is the non-cell Mipox CMP pad. Although made with the same type of polyurethane materials, the Mipox non-cell type does not have micro-pores as the conventional pads do. The apparent density and hardness are therefore slightly higher than those for porous pads. From the onset, the lack of micro-pores on the pad surface may lead to two potential issues . The first is related to the apparent and effective hardness. It has long been established that a harder pad gives higher defect counts. Will the non-cell type Mipox pad give a significant greater defect count when everything else is equal? As shown in Figure 1, the Clarkson-Mipox team found that the defect count for wafers polished using Mipox pads is either similar or lower than that of commercial reference pads.

CAMP’s Annual Technical Meeting was held May 17 - 19, 2006 at the Canandaigua Inn on the Lake in Canandaigua, New York. The very successful meeting had over 100 attendees including representatives of Industry, University, and New York State Economic Development Organizations.

A reception was again hosted by Ferro Electronic Material Systems (a Corporate Sponsor of CAMP).

This year's meeting had a record number of poster presentations on CAMP research. They were judged in three categories: most attractive, most creative, and best overall. Certificates were presented by CAMP's Dr. Dana Barry to the first, second, and third place winners of each category. The judges were Kelly Lee (Infotonics), Dr. Geoffrey Johnson (Engelhard), Dr. Jay Kunzler (Bausch & Lomb), and Dr. David Salloum (Procter & Gamble Company). The winners are listed below.

Dr. Dana M. Barry, senior technical writer and editor at Clarkson University’s Center for Advanced Materials Processing (CAMP), received an APEX 2006 Award for Publication Excellence from Communications Concepts Inc. in Springfield, Va. This is the 11th consecutive time that she has won this award, which is based on editorial content and overall communications effectiveness and excellence. Her winning entry, the “CAMP Annual Report Newsletter 2004-2005,” faired extremely well in the exceptionally intense competition. There were 5,000 entries in the competition and approximately 1,400 awards of excellence were distributed in 102 subcategories of 11 major areas. In addition, Dr. Barry (who also serves as President of the Scientific Board for Ansted University) has been recertified as a Professional Chemist through June 2009 by the National Certification Commission in Chemistry and Chemical Engineering sponsored by the American Institute of Chemists, Inc.